JP2004033899A - Method for treating organic substance of stock carcass and method for producing bone char - Google Patents

Abstract

An object of the present invention is to provide a recycle process for efficiently treating livestock carcass organic matter and washing wastewater from each step in the facility without releasing harmful substances into the environment.
A carbonization step includes at least a fermentation step in which washing wastewater is taken into a livestock carcass organic matter and methane fermentation is performed, and a fermentation product obtained by the methane fermentation is heated and dried and carbonized. The method for treating livestock carcass organic matter, which comprises using biogas generated in the fermentation step as a heat source in the method, and after subjecting the livestock carcass organic matter to methane fermentation, heating and drying the obtained fermented matter. An invention of a method for producing bone char to be carbonized, wherein biogas produced by methane fermentation is used as a heat source in the carbonization step, is disclosed. These methods are processes in which organic substances having a molecular weight of 1,000 or more are not released to the outside.
[Selection diagram] Fig. 1

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for treating livestock carcass organic matter and a method for producing bone charcoal, and more particularly, to a method for treating livestock carcass organic matter that efficiently treats organic matter derived from livestock carcass such as cattle and sheep until it becomes bone charcoal. The present invention relates to a method for producing bone charcoal.
[0002]
[Prior art]
Bone, meat, skin, blood, etc. of livestock and livestock that are not used for meat after collecting meat are processed into meat-and-bone meal, meat meal, blood meal, bone meal, etc. and added to feed, or used as a raw material for fertilizers and various chemical products. It has been reused in a very wide range of applications. However, treatment plants that have been used for the production of meat-and-bone meal and the like consume a lot of energy for pulverization and drying, and require secondary treatment of wastewater and residues.
[0003]
Recently, the discovery of cattle infected with BSE (bovine spongiform encephalopathy) in Japan has banned the addition of meat-and-bone meal to feed as an emergency measure. Most of the organic matter has to be disposed of. In particular, livestock suspected of having BSE must be disposed of, including meat and fat. At this time, it is necessary to avoid releasing abnormal prions that cause BSE to the environment. Therefore, development of a method for safely processing meat-and-bone meal, bone and meat as raw materials thereof, and livestock carcass containing them. Is an urgent issue. At present, such organic matter derived from livestock carcasses is incinerated or otherwise treated with sufficient heat.However, for example, incineration requires fossil energy as an auxiliary fuel. There is a problem that it cannot be used effectively.
[0004]
By the way, as a method for treating organic matter derived from livestock carcass into a safe state, it is possible to change the state to an inorganic state. Bone charcoal and bone ash are known as inorganic substances obtained by processing organic matter derived from livestock carcasses. Among them, bone char is carbonized by heat-treating the organic matter of livestock carcasses at a high temperature under the condition of blocking oxygen, and there is no danger that harmful substances such as abnormal prions remain. Moreover, bone charcoal is very useful as a fertilizer component because it contains a large amount of phosphoric acid, and is a high value-added product because it can also be used as a high-performance adsorbent.
[0005]
However, in order to produce bone char using organic matter derived from livestock carcass as a raw material, heat treatment at a high temperature is indispensable. Therefore, large-scale treatment consumes a large amount of energy as incineration. With sufficient temperature control in carbonization, thorough utilization of by-products as a heat source, and near perfect heat retention, it is not possible to build an energetically independent carbonization process by partially burning pyrolysis products. It is possible. However, such a carbonization facility has not yet been created. Therefore, it is difficult to treat a large amount of livestock carcasses into bone charcoal in existing treatment facilities such as a chemical plant.
[0006]
Japanese Patent Application Laid-Open No. Hei 6-154728 proposes a method of treating organic waste in a fermentation step and a carbonization furnace as a technique using organic waste. However, the fermentation of this technique involves adjusting the water content. It is an aerobic fermentation, and carbonization is a method that requires a lot of energy.
[0007]
Japanese Patent Application Laid-Open No. 2001-276772 proposes a processing method in which a combustible component is obtained from humid organic waste by methane fermentation and used as fuel for a generator. This method is based on the premise that it is not possible to cover the energy of the carbonization process with only gas from methane fermentation, and it is essential to gasify polymer compounds such as plastics by thermal decomposition to produce fuel. .
[0008]
Japanese Patent Application Laid-Open No. H11-77095 proposes a system in which solid matter generated and separated in a livestock dung processing process is carbonized or burned for processing. It is not a method applicable to carcass processing.
[0009]
[Problems to be solved by the invention]
The present invention has been made in view of the above-described circumstances, and is intended to efficiently treat organic matter derived from livestock carcass (that is, livestock carcass organic matter) to inorganic matter without releasing harmful substances into the environment. It is an object of the present invention to provide a resource recycling process.
[0010]
[Means for Solving the Problems]
In order to solve the above problems, an invention of a method for treating livestock carcass organic matter according to claim 1 includes a fermentation step of subjecting livestock carcass organic matter to methane fermentation, and a heat treatment of a fermentate obtained by the methane fermentation. And drying and carbonizing, wherein the biogas generated in the methane fermentation step is used as a heat source in the carbonization step.
[0011]
According to the invention of the method for treating livestock carcass organic matter, a methane fermentation step is provided in the process, and the biogas generated in the methane fermentation step is used as a heat source in the carbonization step, so that the livestock carcass organic matter is directly dried. It is possible to greatly improve the energy balance of the entire process or the recovery rate of the carbide as compared with the current technology of carbonizing. That is, since a part or all of the energy consumed in the carbonization step can be covered by the biogas generated by the methane fermentation, the energy efficiency is very good. Here, “biogas” means a gas mainly composed of methane produced by metabolism of anaerobic microorganisms in methane fermentation.
[0012]
In addition, since organic matter derived from livestock carcass can be converted into high-value-added bone charcoal in the carbonization process with a high yield, it is possible to efficiently recycle livestock carcass organic matter as livestock resources for effective use.
Therefore, the processing method of the present invention is an excellent process capable of keeping running costs low.
[0013]
The invention of the method for treating livestock carcass organic matter according to claim 2 is characterized in that, in claim 1, it is a closed process in which at least an organic substance having a molecular weight of 1,000 or more is not released to the outside.
According to this feature, since it is a closed process in which high molecular organic compounds such as proteins are not released to the outside, harmful substances such as abnormal prions are not released into the environment. In other words, organic matter derived from livestock carcasses can be efficiently converted to inorganic matter as bone char, and water such as washing wastewater generated in each process is also treated in the process.Therefore, water discharged outside the process contains harmful substances. There is no danger.
[0014]
The invention of the method for producing bone char according to claim 3 is a method for producing bone char by heating and drying and carbonizing the obtained fermented material after subjecting the organic matter of the livestock to methane fermentation, and as a heat source in the carbonization step. , Characterized by using biogas produced by methane fermentation.
According to the invention of this method for producing bone char, a methane fermentation step is provided in the process, and the biogas generated in the methane fermentation step is used as a heat source in the carbonization step, so that the livestock carcass organic matter is directly dried and carbonized. Compared with the case of producing bone charcoal, the amount of fossil energy used can be significantly reduced or made unnecessary. In other words, because part or all of the energy consumed in the carbonization step can be covered by biogas generated by methane fermentation, the energy efficiency of the entire process is very good, and high value-added bone coal can be produced at low cost. Becomes possible. In addition, it becomes possible to recycle and effectively utilize the livestock carcass organic matter as livestock resources without discarding it.
Therefore, the manufacturing method of the present invention is an excellent process capable of keeping running costs low.
[0015]
The invention of the method for producing bone charcoal according to claim 4 is characterized in that, in claim 3, it is a closed process in which at least an organic substance having a molecular weight of 1,000 or more is not released to the outside.
According to this feature, since it is a closed process in which high molecular organic compounds such as proteins are not released to the outside, harmful substances such as abnormal prions are not released into the environment. In other words, in addition to efficiently converting organic matter derived from livestock carcasses to inorganic matter as bone char, water such as washing wastewater generated in each process is also treated in the process, so water discharged outside the process contains harmful substances. There is no danger.
[0016]
BEST MODE FOR CARRYING OUT THE INVENTION
The method for treating livestock carcass organic matter of the present invention is a fermentation step of subjecting livestock carcass organic matter to methane fermentation, and a carbonization step of heating and drying and carbonizing the fermented product using biogas obtained by the methane fermentation as a heat source. And at least these steps are performed sequentially.
[0017]
The organic matter derived from livestock carcass or the like in the present invention, that is, livestock carcass organic matter refers to animal waste containing cartilage, carcasses and / or processed products thereof, and specifically, cattle, sheep, goats, In addition to carcasses of livestock such as chickens, bones, meat, fat, internal organs, blood, brain, eyeballs, skin, hooves, horns, etc., separated therefrom, for example, meat and bone meal, meat meal, bone meal, blood meal, etc. In addition, a crushed product obtained by crushing bones and meat of a livestock carcass and a dried product obtained by drying blood and the like are also included.
[0018]
<Crushing process (pretreatment)>
In the treatment method of the present invention, a crushing / separation step can be carried out as a pretreatment as necessary, depending on the state of the livestock carcass organic matter as a raw material.
The crushing / separating step can be performed by, for example, the following crushing / fractionation or whole crushing.
In the case of the fractional crushing, a crushable fractionator is used to collect the easily crushable part in the livestock carcass as a slurry together with the liquid. On the other hand, parts that are difficult to crush are separately collected as a lump. The water content of the slurry is about 70 to 90% by weight, and the water content of the lump is about 40 to 60% by weight. The crushing and sorting machine crushes organic solids by shearing force and pulling force, and a cutter part of a two-axis type or a three-axis type can be used. Animal carcasses such as cows are preferably crushed by a triaxial method from the viewpoint of fineness and uniformity of crushing.
[0019]
The mixed plastics, sheets, and the like to be sorted and removed can be removed by mesh sorting, wind sorting (wind sorting), or the like.
[0020]
Further, in the case of the whole amount pulverization, all the objects are crushed using a crusher such as a disposer. The water content is averaged for carcasses, for example, 60-70% by weight, but for processed products, it is wide.
[0021]
<Fermentation process>
In the methane fermentation step of the present invention, any of a so-called medium temperature type, a high temperature type, a slurry (wet type) type, and a dry (dry type) type can be applied.
[0022]
In order to maintain the activity of the anaerobic methane fermentation bacterium, the fermentation tank is constituted by a tank in which air is completely shut off in the latter stage even in the case of a fermentation process using a two-tank method. The shape and operating conditions of the fermenter differ depending on the solid concentration (usually in the range of 7% to 40% by weight) and the fermentation temperature (usually 37 ° C. for medium-temperature fermentation and 55 ° C. for high-temperature fermentation). In particular, in the present invention, in the case of a raw material having a high water content (up to a solid concentration of 10% by weight) due to mixing of washing wastewater or the like, a wet-type complete mixing fermenter, a raw material with a low water content (solid When the concentration is 30 to 40% by weight), it is preferable to use a so-called dry plug flow type (extrusion type) fermenter.
[0023]
It is preferable that the fermenter be provided with a heating means for keeping the temperature as required, in addition to a collecting means for collecting the produced biogas. In addition, a desulfurization device may be provided in the biogas recovery means as needed. These can have a known configuration.
[0024]
In the case of a raw material having a high moisture content (solids concentration up to about 10% by weight), a completely mixed fermentation tank is used, and the retention time (Retention Time) of the high-temperature methane fermentation bacterium (optimum temperature 55 ° C.) is 10 For a medium-temperature methane fermentation bacterium (optimum temperature 37 ° C.) for about a day, the residence time can be shorter than about 15 to 20 days, which is shorter than the required number of days for normal methane fermentation. In the present invention, unlike the usual anaerobic digestion treatment, methane fermentation is performed for the purpose of recovering methane, so it is not necessary to perform the decomposition treatment by methane fermentation until completion. In addition, in general methane fermentation, the residence time is about 15 days for high temperature fermentation and about 20 to 30 days for medium temperature fermentation.
[0025]
In the case of a raw material having a low moisture content (solids concentration of 30 to 40% by weight), the solid content concentration of the object to be treated is adjusted to 30 to 40% by weight, and the hardness is adjusted to such an extent that an extrusion fermenter can be used. The residence time can be set as in the case of the high water content. If necessary, some organic components can be introduced for adjusting the carbon / nitrogen ratio.
[0026]
The main purpose of providing the methane fermentation step in the treatment method of the present invention is to recover biogas as an energy source. The recovery of energy by biogas secures the energy independence of the carbonization process in that high-quality fuel can be recovered compared to energy recovery by thermal decomposition during carbonization. In contrast, current carbonization furnaces require a supplemental fuel, especially when the temperature rises, or burn some of the carbonized components (reducing the carbonization yield) to cover the required energy. .
[0027]
<Solid-liquid separation>
In the treatment method of the present invention, a solid-liquid separation step of the fermentation liquid can be provided as necessary after the methane fermentation treatment. In order to suppress energy consumption in the subsequent carbonization step, it is preferable to perform solid-liquid separation to reduce the initial moisture content in the carbonization step.
[0028]
For solid-liquid separation, for example, a device capable of increasing the slurry concentration such as a decanter, a coagulating sedimentation tank, a centrifugal dehydrator, a screw press, and a membrane separator can be used, and is selected according to the properties of the fermentation liquid. In addition to the above, a solid-liquid separation method by an evaporation method is also possible. In this case, biogas produced by methane fermentation can be used as an energy source for evaporation.
[0029]
<Carburizing process>
In the carbonization step, the fermented product or the like is carbonized by heating the fermented product or the like to a predetermined temperature under the condition that the air is shut off. In the treatment method of the present invention, as described above, biogas recovered in the methane fermentation step can be used as a heat source in the carbonization step.
[0030]
Examples of the apparatus used in the carbonization step include a drying / carbonization apparatus capable of shutting off outside air, such as a rotary kiln type, a screw conveyor type, a gravity drop type, and a batch fixed bed type. When drying and carbonizing at a relatively low temperature (450 to 500 ° C.), any method can be used. However, when drying and carbonizing at a high temperature of 800 ° C. or more, mechanical methods such as a rotary kiln method and a screw conveyor method are used. It is important to select a heat-resistant material in a drying / carbonizing apparatus with large elements. The carbonization treatment at 800 to 850 ° C. can improve the recovery rate of combustible gas from organic matter of livestock carcass.
[0031]
In the carbonization step, gas is generated as the organic matter is thermally decomposed. This pyrolysis gas is preferably used as a heat source in the carbonization step by being recovered.
[0032]
<Secondary processing>
The liquid after solid-liquid separation is reused and discharged by distillation, oxidation with an oxidizing agent, catalytic oxidation, and membrane separation so as not to contain at least a high molecular weight organic substance having a molecular weight of 1,000 or more. The main use for reuse is as washing water in each process including the dismantling site.
[0033]
Next, a representative example of the processing method of the present invention will be described with reference to the drawings.
FIG. 1 is a flowchart showing an outline of a method for treating livestock carcass organic matter according to the first embodiment of the present invention. This method is a method suitable for, for example, a target of a livestock carcass organic substance containing a partially dismantled livestock carcass as a lump.
[0034]
In this method, first, a portion of a carcass that is difficult to crush in a crushing separation step is separated as a lump, and the lump is directly input to a carbonization step. On the other hand, the crushed material is sequentially subjected to a fermentation step and a solid-liquid separation step under the conditions described above. In the fermentation step, biogas is collected and used as a heat source for heating in the carbonization step. The liquid component generated in the solid-liquid separation step can be used for washing water in another step after the secondary treatment or for water adjustment before the fermentation step. Although water after solid-liquid separation may be used directly for water adjustment in the fermenter, it is important to incorporate a secondary treatment step that can remove ammonia and the like. In the carbonization step, the mass obtained from the crushing and fractionation step and the fermented product that has undergone the fermentation step and the solid-liquid separation step are heated to a predetermined temperature to carbonize.
[0035]
As an example of the process in FIG. 1, about 50% by weight of the raw material is separated as lumps in a crushing and separating step, and the remaining 50% by weight is subjected to methane fermentation in a fermentation step using a mixed fermenter as a slurry having a solid content of 10% by weight. Do. The fermented liquor (fermented product after methane fermentation) increases the amount (volume) of the raw material by about 20% to adjust the water content, but by subjecting it to a solid-liquid separation step, the increased amount is separated as a liquid component. . Almost the same amount as the remaining raw material (carcass organic matter and fermentation residue) is subjected to a carbonization process to be mineralized to bone char. The liquid separated in the solid-liquid separation step can be used for washing water in another step after the secondary treatment and water adjustment in the fermentation step.
[0036]
FIG. 2 is a flowchart showing an outline of a method for treating livestock carcass organic matter according to the second embodiment of the present invention. This method is a method suitable mainly for processing already processed livestock carcass organic matter such as meat-and-bone meal.
[0037]
In this method, first, a livestock carcass organic substance as a raw material is sufficiently crushed in a crushing step, and then sequentially subjected to a fermentation step and a solid-liquid separation step under the above-described conditions. In the fermentation step, biogas is collected and used as a heat source for heating in the carbonization step. The liquid component generated in the solid-liquid separation step can be used for washing water in another step after the secondary treatment and for adjusting the water content before the fermentation step. In the carbonization step, the fermented product that has undergone the fermentation step and the solid-liquid separation step is heated to a predetermined temperature and carbonized.
[0038]
In FIG. 2, when a mixture of, for example, beef carcass and meat-and-bone meal (for example, a water content of about 60% by weight) is considered as a raw material, the whole amount is crushed in a crushing and fractionation step, and water is adjusted to a water content of about 75% by weight. Perform methane fermentation in the fermentation process. The amount of fermented product after methane fermentation increases by 50% or more. By subjecting the fermented product to a solid-liquid separation step, it is possible to separate an increased amount of liquid. The solid content is subjected to a carbonization process to be mineralized to bone char. After the secondary treatment, the liquid separated in the solid-liquid separation step can be circulated to each step as washing water in another step, or can be circulated to the fermentation step to be used for water adjustment.
[0039]
The treatment method of the present invention is a closed treatment process in which high-molecular-weight organic compounds other than mineralized bone charcoal are not released to the outside. As will be shown in Examples described later, the substances finally released into the environment are bone char, excluding the combustion exhaust gas such as carbon dioxide, and the condensed water generated in the carbonization step and the cleaning generated in other process cleaning steps. This is treated water obtained by subjecting waste water to secondary treatment to completely remove high molecular organic compounds. Condensed water may contain low molecular weight volatile components (eg, volatile fatty acids, amino acids, etc.), while washing wastewater may contain carcass-derived components. Therefore, the washing wastewater is subjected to heat / pressure treatment, membrane treatment, adsorption treatment, distillation treatment and the like so that no high-molecular organic compound is released to the outside, and the wastewater is reused. As a method for reliably removing a high molecular weight substance, there is a film processing method using a UF film, NF film, RO film, or the like.
[0040]
The method for producing bone charcoal according to the present invention is characterized in that crushed material obtained by crushing livestock carcass organic matter is subjected to methane fermentation treatment, and then the resulting fermented material is heated and dried / carbonized. This method of producing bone charcoal can be carried out by performing a methane fermentation treatment step, a carbonization step, and the like according to the above-described method for treating livestock carcass organic matter. Details of each step are as described above, and thus description thereof is omitted. The bone char obtained by the production method of the present invention is ensured in safety, and has high utility value, for example, as a feed, a fertilizer, a soil conditioner, a snow melting material, a deodorant, and a filter.
[0041]
[Action]
The methane fermentation step in the method of the present invention is carried out mainly from the viewpoint of securing safety in energy acquisition and resource utilization. In the method for treating livestock carcass organic matter of the present invention, by incorporating methane fermentation treatment as an essential step in the treatment process, the biogas obtained therefrom (main component of methane gas) is used as a heat source for the subsequent carbonization step. I do. This process is based on the premise that the organic matter from carcass can be converted into completely detoxified inorganic matter such as bone charcoal when it is recycled. It is also an important object of the process to treat washing wastewater generated at various places in the process and dismantling sites and to regenerate water that does not contain high molecular organic compounds such as proteins.
[0042]
In order to mineralize the livestock carcass organic matter, the livestock carcass organic matter can be directly subjected to the carbonization process without performing methane fermentation, but by using this carbonization process, carbonization is promoted while efficiently collecting energy. In order to achieve this, it is necessary to use energy from the combustion of liquids and solids or to introduce energy from the outside. In general, when livestock carcass organic matter is directly pyrolyzed at a relatively low temperature of about 500 ° C., the amount of generated hydrocarbons is small and CO ₂ And N ₂ Is mainly generated, and a relatively large amount of gas such as ammonia and hydrogen sulfide is generated. When pyrolysis is performed at such a relatively low temperature, the generated gas has a very low value as a fuel, and it is indispensable to obtain a heat source by burning a liquid or solid.
[0043]
On the other hand, in the present invention, biogas is produced from the raw material by methane fermentation treatment, and the biogas is collected and used as an energy source in the carbonization step. Therefore, a process with extremely excellent energy use efficiency can be provided. In addition, livestock carcass organic matter is a raw material that is advantageous for methane fermentation because of its high fat content and the like, and is an optimum raw material for performing methane fermentation treatment for the purpose of energy recovery.
[0044]
Recovering biogas from livestock carcass organic matter by methane fermentation, as shown in the Examples below, reduces the loss of organic matter in the carbonization process, in addition to the significance of efficiently converting it to bone charcoal, This has the significance that it is possible to efficiently and reliably treat the cleaning wastewater which has been insufficiently treated by biological treatment or the like.
That is, when the organic matter of the livestock carcass is thermally decomposed as it is, many organic substances are easily converted into liquid products (tar), solid products (including char), carbon dioxide, etc., and are easily lost, which tends to lower the yield of bone charcoal. However, the problem can be improved by performing methane fermentation in advance.
[0045]
As described above, the method of the present invention focuses on the usefulness of livestock carcass organic matter as an energy source, converts livestock carcass organic matter into energy by methane fermentation, solves problems in wastewater treatment, and provides high value-added bone coal. Is made possible.
[0046]
【Example】
Next, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited thereto.
Example 1
Based on the process chart shown in FIG. 3, slaughtered carcasses such as cows were processed.
That is, the raw material was crushed by the primary crushing and sorting machine 10 of the biaxial type and the rough screen sorting type, and the primary crushing treatment was performed. The separated mass (about １ ／ of the raw material) was directly charged into a screw conveyor type drying / carbonizing device 40.
[0047]
The crushed material after the primary crushing treatment (about の of the raw material; water content about 87%) was subjected to secondary crushing treatment by a secondary crushing and sorting machine 11 of a triaxial type and a screen sorting type. Next, after the solid concentration was adjusted to 8 to 10% by weight, the mixture was transferred to a complete mixing type fermenter 20 and subjected to methane fermentation at a temperature of 55 ° C. for a residence time of 7 days. After the methane fermentation, the fermented product was processed by a solid-liquid separator 30 of a centrifugal separation method, and about 80% by weight of the solid content side was transferred to a carbonization step. On the other hand, the liquid component occupying about 20% by weight of the fermented liquid was returned to the fermentation step and used for water adjustment during fermentation. During fermentation, biogas having a methane concentration of 55 to 65% by weight was produced, and was used as an energy source for the next carbonization step.
[0048]
In the carbonization step, the carbonization product (bone charcoal) was obtained at about 1/4 with respect to the weight of the raw material by treating at 500 ° C. using a screw conveyor type drying / carbonization apparatus 40.
An organic compound having a molecular weight of 200 to 300 or more and a coloring component were removed from the condensed water generated in the carbonization step using an NF film (loose RO film, NTR-7250). The condensed water treated by the filtration membrane 50 was used as washing water as regenerated water. In addition, solid-liquid separation of the fermentation liquid is performed by the evaporation method, and the distillate is reused for diluting the fermentation step and for washing each step after passing through the NF membrane, and the excess is used to confirm the amount of organic acids and the like by gas chromatography analysis. And released.
[0049]
Comparative Example 1
In Example 1, the entire amount of carcass treated by the triaxial secondary crushing and sorting machine 11 without the methane fermentation treatment was directly charged into the drying and carbonizing device 40 to perform the drying and carbonizing treatment. In this case, it is necessary to use a liquid product (tar) or a solid product (including char) as a heat source due to the nature of the pyrolysis gas having a small amount of flammable components. As a result, energy efficiency is reduced and carbonization products are reduced. The yield of (bone charcoal) was reduced to about 60% of Example 1.
[0050]
As described above, the results of Example 1 and Comparative Example 1 show that it is important in the present recycling process to provide a methane fermentation step and secure a gas serving as a fuel.
The composition of the biogas produced in the methane fermentation step in Example 1 is about 55 to 65% by weight of methane, 45 to 35% by weight of carbon dioxide, about 1,000 to 2,000 ppm of hydrogen sulfide, and about 50% of ammonia on a dry basis. It was about 300 ppm. On the other hand, in Comparative Example 1, the composition of the pyrolysis gas generated in the carbonization step at 500 ° C. was such that the combustible components (carbon monoxide, hydrogen, hydrocarbons, etc.) were 10% by weight or less on a dry basis, and nitrogen gas, It was carbon gas. The large amount of carbon dioxide produced is disadvantageous in terms of energy efficiency.
[0051]
Example 2
Based on the process diagram shown in FIG. 4, a carcass such as a cow and a green agricultural waste such as vegetable waste were mixed and treated.
That is, after the mixture of the raw materials is crushed by the triaxial crusher 12, the total amount of the crushed material is adjusted to 90 to 92%, and then transferred to the fermentation tank 21. did. An energy source for the carbonization process was secured by biogas generated during fermentation.
[0052]
After methane fermentation, the fermented liquor was subjected to solid-liquid separation by a solid-liquid separator 30 of a screw press type, and the solid content side was put into a drying / carbonizing device 40. The other liquid was returned to the fermentation step and used for water adjustment during fermentation.
[0053]
In the carbonization step, using a screw conveyor type drying / carbonization apparatus 40, the carbonization was performed at 450 to 550 ° C., thereby obtaining about 1/3 of the bone char with respect to the raw material weight. The condensed water generated in the carbonization process contains a small amount of low-molecular-weight organic compounds such as volatile fatty acids, organic acids and amino acids, but is removed by filtration with an NF membrane (loose RO membrane, NTR-7250). It was confirmed that it was possible. The condensed water treated by the filtration membrane 50 was reused for cleaning as regenerated water. In addition, it was confirmed that a polymer having a molecular weight of 1,000 or more was excluded even in a filtration treatment using a UF membrane (Ultrafiltration, NTU-2000).
[0054]
Comparative Example 2
In Example 2, the entire amount of carcass treated by the crusher 12 without the methane fermentation treatment was directly charged into the drying / carbonizing device 40 to perform the drying / carbonizing treatment. As a result, the yield of the carbonized product (bone charcoal) was reduced to about ／ of Example 2. In addition, if 80% or more of the pyrolysis products and products were not used as fuel, a self-sustaining energies could not be obtained.
[0055]
Example 3
Based on the process diagram shown in FIG. 5, meat-and-bone meal of beef and the like was processed. This process did not include a solid-liquid separation step, and the entire amount of the fermentation residue was put into a dry carbonization device.
[0056]
That is, meat-and-bone meal (average moisture content: 3 to 5% by weight) as a raw material was separated by a 10 mm mesh screen 13 and large solids were sufficiently crushed by a triaxial crusher 14.
[0057]
The crushed material after the crushing treatment and the meat-and-bone meal passed through the screen 13 were charged into the mixing tank 15 and mixed to adjust the water content to about 75% by weight. Condensed water and washing wastewater were used as water for adjusting the water content.
[0058]
Next, the whole amount of the mixture (water content: about 75% by weight) was transferred to the fermenter 21 of a horizontal extrusion system, and subjected to methane fermentation at a temperature of 55 ° C. for a residence time of 7 days. One third of the residue after the fermentation treatment was returned to the mixing tank outlet for breeding and mixed with fresh fermentation raw materials. The biogas generated in the fermenter was used as an energy source for the next carbonization step.
[0059]
After the methane fermentation, the fermented product was put into the drying / carbonizing device 40.
In the carbonization step, using a screw conveyor type drying / carbonization apparatus 40, the carbonization was performed at 450 to 550 ° C., thereby obtaining about 1/3 of the bone char with respect to the raw material weight. Evaporation and condensed water generated in the carbonization process contain a small amount of relatively low-molecular-weight organic compounds such as volatile fatty acids and amino acids. It can be treated and used as washing water, or surplus can be discharged.
[0060]
Comparative Example 3
In Example 3, the whole amount of meat-and-bone meal separated by the screen without the methane fermentation treatment was directly charged into the drying / carbonizing device 40 to perform the drying / carbonizing treatment. When the required energy of the carbonization furnace was covered by the liquid component and the solid content decomposed in the carbonization furnace, the yield of the carbonized product (bone charcoal) was reduced to about ３ of that in Example 3.
[0061]
【The invention's effect】
In the method for treating livestock carcass organic matter of the present invention, a methane fermentation step is provided in the process, and biogas generated in the methane fermentation step is used as a heat source in the carbonization step. This improves the energy balance of the entire process as compared with the case where the cleaning process is performed, and enables the construction of a system including the treatment of the cleaning wastewater. It is difficult to carry out general biological treatment of this washing wastewater similarly to the treatment of the methane fermentation liquid, and it can be easily realized by treatment using methane fermentation and carbonization.
[0062]
In addition, since the organic matter derived from the livestock carcass can be converted into high-value-added bone char in the carbonization process, the livestock carcass organic matter as livestock resources can be recycled and effectively used.
[Brief description of the drawings]
FIG. 1 is a flowchart showing an outline of a first embodiment of a process for treating livestock carcass organic matter according to the present invention.
FIG. 2 is a flow chart showing an outline of a second embodiment of a process for treating livestock carcass organic matter according to the present invention.
FIG. 3 is a flowchart showing an outline of a process according to the first embodiment.
FIG. 4 is a flowchart showing an outline of a process according to a second embodiment.
FIG. 5 is a flowchart showing an outline of a process according to a third embodiment.
[Explanation of symbols]
10 Primary crushing and sorting machine
11 Secondary crushing and sorting machine
12 Crusher
13 screen
14 Crusher
15 mixing tank
20, 21 Fermenter
30 Solid-liquid separator
40 Drying and carbonizing equipment
50 filtration membrane

Claims (4)

1. Fermentation process of methane fermentation of livestock carcass organic matter, and
   A carbonization step in which the fermented product obtained by the methane fermentation is subjected to a heat treatment, dried, and carbonized,
   Wherein at least the biogas produced in the fermentation step is used as a heat source in the carbonization step.
2. 2. The method for treating livestock carcass organic matter according to claim 1, wherein the closed process has no release of organic matter having a molecular weight of 1,000 or more to the outside.
3. After the methane fermentation treatment of livestock carcass organic matter, a method for producing bone char to dry and carbonize the resulting fermented product,
   A method for producing bone charcoal, comprising using biogas generated by methane fermentation as a heat source in a carbonization step.
4. 4. The method for producing bone char according to claim 3, wherein the process is a closed process in which at least an organic substance having a molecular weight of 1,000 or more is not released to the outside.

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